With simple electronic devices having only a few functions, a user readily knows when the device malfunctions, e.g., a broken switch fails to provide the expected input when actuated. With complex electronic devices having various functions, however, a user may not be able to determine if a particular function is malfunctioning until the user attempts to execute that function. For example, a user will not know that a disk drive on his or her computer is malfunctioning until the computer performs a read/write function from/to the disk drive.
Several electronic devices currently available provide automatic self-testing upon power-up of the device. For example, a typical personal computer ("PC") performs a power-on self-test, or "POST," each time the PC is powered up. The POST detects errors in the display monitor, the keyboard, the memory, and other basic components within the PC, and produces one or more error messages on the display (or a series of beeps if the display is malfunctioning). A single beep combined with a display of the normal prompt on the display indicate that all components have passed the POST.
Simple and quickly executable self-tests are performed for most complex electronic devices. For example, in the PC, the POST checks the random access memory. ("RAM") by simply writing data to each memory location in RAM or series of memory locations, and then reading the data back and comparing it to the data initially written to the memory location. More sophisticated, and accurate, memory tests may be performed. The "walking pattern test" is a known RAM test that writes a value to all of the memory locations in RAM and then writes a new value to only one memory, location. All memory locations are then read to determine if the value in the one memory location equals the new value written thereto, and to determine if all the other memory locations have been changed by the writing of the new value to the one memory location. This test continues for each memory location by writing the new value thereto and then reading the values in all memory locations. This test requires a considerable amount of computer processing time. For example, the walking pattern test takes two to three minutes to test 130,000 bytes of RAM. As a result, the walking pattern test is not performed during most RAM self-tests such as the POST. Similarly, while a cyclic redundancy check ("CRC") is known in the art to be a more accurate but time-consuming method of testing read only memory ("ROM"), a quick checksum test is performed instead during most self-tests such as the POST.
With emergency electrical equipment, self-testing before an emergency is important to insure that the equipment is functioning properly and reliably. The emergency equipment, however, must also be available for immediate use. Lengthy self-tests of the emergency equipment prohibit the equipment from being used for its intended purpose while the tests are being performed. Delaying treatment to perform extensive self-tests could threaten a victim's health. Therefore, extensive and lengthy self-tests are impractical for emergency electronic equipment. Most of the components in the equipment that require time-consuming tests to insure their proper functioning are simply not tested during power-up of the equipment.
For example, portable defibrillator units currently available only perform the simple read/write tests of the RAM described above and checksum tests of the ROM; extensive tests of the defibrillating components are not performed. These critical components, which provide an electric charge to a patient, are tested only during manufacturing of the defibrillator unit. An operator of the defibrillator unit must therefore submit the unit to regular testing by a skilled technician to ensure that the components not subjected to a self-test are operating properly. These regularly scheduled maintenance periods require downtime for the unit, even if the unit is functioning properly.
Overall, the inventors are unaware of a portable emergency electronic device which provides time-consuming yet thorough tests of its own components while still allowing the device to be readily available in the event of an emergency.